Hi Kristin,
I think the place you are looking for could be NURNBERG, in Bavaria. I found it on a map of Germany on the internet.
I went to
www.geneanet.org and searched for Schwarz at Nurnberg and came up with one database owned by a Michael Klein in Berlin.
(
http://www.goklein.de)
He may be able to help you.
I would also recommend
www.familysearch.org (Latter Day Saints)
I have had amazing success with the Kirchenbuch - German parish records, for my mother's family who were from Prussia.
I ordered the film for the village where they came from in Prussia and found out that my 2nd great grandfather had 2 other wives and 6 other children who we did not know about.
The records are in a mixture of Latin and German but are not too difficult to interpret and there are on-line lists available, of German and Latin words which relate to genealogy.
(I checked the IGI at the LDS website but did not see your John there.)
Please let me know what you think about the location being NURNBERG - that's how it appears to me.
I may be able to help you with Katharine Kroll's place of birth but the map site I require is not available at the moment.
Hope this gives you some help and encouragement.
Foxglove